I think it's important to note that the D3 folks are not only the last to board if space is available, but way too often they are not treated very nicely by the gate agents, ane way back when I used D2 privileges, many a time it took 2 or 3 days even to leave from LAS or ORD...so I guess my point is that in addition to flexibility and patience, you should have a pretty thick skin. Have seen flight privileges pulled from employees because their D3 were less than polite. (not saying you would be less than polite, just after 3 days or so of trying to get on a plane, even the nicest folks may be grumpy)